Worth noting explicitly is that the CICS alternatives are o THREADSAFE and o QUASIRENT. Long before IBM COBOL compilers could generate reentrant code COBOL was made usable for CICS APs by trickery. The pointer to working storage--There was as yet no stack-based local storage, and COBOL programmers still use it very/too little--was at a standard location within a COBOL load module; CICS was therefore able to alter it for each [CICS] task to make it point to a distinct instance of [dynamically allocated] working storage. This required serialization and other housekeeping, and the scheme used was for this reason described as "making COBOL [not reentrant but] quasi-reentrant". Moreover, I believe that CICS still does this for some old COBOL APs. However that may be, the wide use of the term quasi-reentrant made the unqualified term reentrant problematic in a CICS environment: it was judged better to use the new term thread-safe, which had no unhappy connotations, instead. On this and other C/S topics WICKIPEDIA pieces are problematic. At least in my experience they are not usually, after a time, wrong; but they do very often embody assumptions appropriate to some single hardware-architecture and operating-system environment, and words like reentrant are defined and used differently in different such environments. Initially in an IBM mainframe environment a reentrant program could modify itself, usually at initial-load time, if it held a global lock while it did so; and this is the chief reason why a stronger term, refreshable in the event, was needed, introduced, and used. In fact the routines I write in assembly language, PL/I, or (when sometimes I must) C are always both reentrant and refreshable; they never alter themselves, using dynamic heap (non-LIFO) and stack (LIFO) storage in classical fashion to avoid doing so; and I believe that this is the practice of many other contributors to IBM-MAIN.
John Gilmore Ashland, MA 01721-1817 USA ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
